Scientists have found a way to produce cartilage tissue by 3D bioprinting an ink containing human cells, that may lead to personalised implants to heal damaged noses, ears and knees.

The researchers have successfully tested the technology in an in vivo mouse model. Athletes, the elderly and others who suffer from injuries and arthritis can lose cartilage and experience a lot of pain.

"Three-dimensional bioprinting is a disruptive technology and is expected to revolutionise tissue engineering and regenerative medicine," said Paul Gatenholm, from Wallenberg Wood Science Centre in Sweden.

"Our team's interest is in working with plastic surgeons to create cartilage to repair damage from injuries or cancer," said Gatenholm. "We work with the ear and the nose, which are parts of the body that surgeons today have a hard time repairing. But hopefully, they'll one day be able to fix them with a 3D printer and a bioink made out of a patient's own cells," he said.

The researchers first had to develop an ink with living human cells that would keep its shape after printing.

To create a new bioink, they mixed polysaccharides from brown algae and tiny cellulose fibrils from wood or made by bacteria, as well as human chondrocytes, which are cells that build up cartilage.

Using this mixture, the researchers were able to print living cells in a specific architecture, such as an ear shape, that maintained its form even after printing. The printed cells also produced cartilage in a laboratory dish.

"But under in vitro conditions, we have to change the nutrient-filled liquid that the material sits in every other day and add growth factors," Gatenholm said.

The next step was to move the research from a lab dish to a living system. The team printed tissue samples and implanted them in mice. The cells survived and produced cartilage. To boost the number of cells, the researchers mixed the chondrocytes with human mesenchymal stem cells from bone marrow.

Previous research has indicated that stem cells spur primary cells to proliferate more than they would alone. Preliminary data from in vivo testing over 60 days show the combination does indeed encourage chondrocyte and cartilage production.